Camera module

ABSTRACT

The present invention relates to a camera module having an auto focus function, the module including a lens unit having at least one lens, a barrel into which the lens unit is inserted, and connected by a VCM (Voice Coil Motor) actuator, and an image sensor discretely positioned from the lens unit to convert light having passed the lens unit to an electrical signal, where the VCM actuator includes a gap of a reference distance position value which is a position of an object catering to a lens focal length according to the camera module, and information on a focus-met lens position value, and adjusts an initial position of the lens by using the gap of reference distance position value of the lens position value during operation of the camera module.

TECHNICAL FIELD

The present invention relates to a camera module camera module having anauto-focus function.

BACKGROUND ART

Digital camera modules are currently being incorporated into a varietyof host devices. Such host devices include cellular telephones, personaldata assistants (PDAs), computers, and so forth. Consumer demand fordigital camera modules in host devices continues to grow.

The camera modules having auto focus adjusting function is configuredsuch that a barrel protecting a conventional lens unit is coupled to abobbin wounded by a coil via a screw, where the bobbin is interposedbetween a holder adhesively contacted at a floor surface thereof to aprinted circuit board and a motor base.

However, the thus-configured camera module is disadvantageous in that anoptical tilt and shift may be generated by unevenness of adhesive coatedfor assembling multiple components and assembly tolerance in componentsto decrease the quality of images due to accumulated errors. Anotherdisadvantage is that separate focus adjustment process is inevitablyneeded after assembly of each component due to the assembly tolerance incomponents.

DISCLOSURE OF THE INVENTION Technical Problem

The present invention is disclosed to provide a camera module configuredto integrate bobbins including a barrel and a coil to minimize anoptical tilting and to free a separate manual focus adjusting processafter assembly of each component.

Technical problems to be solved by the present invention are notrestricted to the above-mentioned, and any other technical problems notmentioned so far will be clearly appreciated from the followingdescription by skilled in the art.

Solution to Problem

An object of the invention is to solve at least one or more of the aboveproblems and/or disadvantages in a whole or in part and to provide atleast the advantages described hereinafter. In order to achieve at leastthe above objects, in whole or in part, and in accordance with thepurposes of the invention, as embodied and broadly described, and in onegeneral aspect of the present invention, there is provided a cameramodule having an auto focus adjustment function, the cameracharacterized by: a lens unit including at least one lens; a barrel intowhich the lens unit is inserted, and connected by a VCM (Voice CoilMotor) actuator; and an image sensor discretely positioned from the lensunit to convert light having passed the lens unit to an electricalsignal, where the VCM actuator includes a gap of a reference distanceposition value which is a position of an object catering to a lens focallength according to the camera module, and information on a focus-metlens position value, and adjusts an initial position of the lens byusing the gap of reference distance position value of the lens positionvalue during operation of the camera module.

In another general aspect of the present invention, there is provided acamera module, characterized by: a lens unit including at least onelens; a barrel into which the lens unit is inserted; and abarrel-connected VCM (Voice Coil Motor) actuator adjusting an initialposition of the lens by using a gap of a reference distance positionvalue which is a position of a lens focus-met object or information on alens position value at a focus-met area.

Advantageous Effects of Invention

The camera module having an auto focus adjusting function according tothe present invention has an advantageous effect in that a barrel and abobbin are integrated to minimize a defect in picture image by anoptical tilting generated by assembly tolerance in a plurality ofcomponents, and to shorten an assembly process of components to remove aseparate manual focus adjusting process during manufacturing of thecamera module and to save the manufacturing cost.

BRIEF DESCRIPTION OF DRAWINGS

The teachings of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 is a cross-sectional view illustrating an example of a cameramodule having an auto focus adjusting function;

FIG. 2 is a cross-sectional drawing illustrating a camera module havingan auto focus adjusting function according to an exemplary embodiment ofthe present invention;

FIG. 3 is a block diagram illustrating a VCM actuator driver accordingto an exemplary embodiment of the present invention;

FIG. 4 is a flowchart illustrating an example of a camera module havingan auto focus adjusting function according to an exemplary embodiment ofthe present invention; and

FIG. 5 is a flowchart illustrating a method of calibrating a referencedistance position value according to an exemplary embodiment of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The following description is not intended to limit the invention to theform disclosed herein. Consequently, variations and modificationscommensurate with the following teachings, and skill and knowledge ofthe relevant art are within the scope of the present invention. Theembodiments described herein are further intended to explain modes knownof practicing the invention and to enable others skilled in the art toutilize the invention in such, or other embodiments and with variousmodifications required by the particular application(s) or use(s) of thepresent invention.

The disclosed embodiments and advantages thereof are best understood byreferring to FIGS. 1-5 of the drawings, like numerals being used forlike and corresponding parts of the various drawings. Other features andadvantages of the disclosed embodiments will be or will become apparentto one of ordinary skill in the art upon examination of the followingfigures and detailed description. It is intended that all suchadditional features and advantages be included within the scope of thedisclosed embodiments, and protected by the accompanying drawings.Further, the illustrated figures are only exemplary and not intended toassert or imply any limitation with regard to the environment,architecture, or process in which different embodiments may beimplemented. Accordingly, the described aspect is intended to embraceall such alterations, modifications, and variations that fall within thescope and novel idea of the present invention.

Meanwhile, the terminology used herein is for the purpose of describingparticular implementations only and is not intended to be limiting ofthe invention. That is, as used herein, the singular forms “a”, “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed itemsand may be abbreviated as “/”.

It will be further understood that the terms “comprises” and/or“comprising,” or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof. That is, the terms “including”, “includes”, “having”,“has”, “with”, or variants thereof are used in the detailed descriptionand/or the claims to denote non-exhaustive inclusion in a manner similarto the term “comprising”.

Also, “exemplary” is merely meant to mean an example, rather than thebest. If is also to be appreciated that features, layers and/or elementsdepicted herein are illustrated with particular dimensions and/ororientations relative to one another for purposes of simplicity and easeof understanding, and that the actual dimensions and/or orientations maydiffer substantially from that illustrated.

That is, in the drawings, the size and relative sizes of layers, regionsand/or other elements may be exaggerated or reduced for clarity. Likenumbers refer to like elements throughout and explanations thatduplicate one another will be omitted.

Now, the present invention will be described in detail with reference tothe accompanying drawings.

FIG. 1 is a cross-sectional view illustrating an example of a cameramodule having an auto focus adjusting function.

A camera module (100) having an auto focus adjusting function mayinclude a lens unit (110), a barrel (120), a bobbin (130), a magnet(140), an infrared filter (150), an image sensor (160), a printedcircuit board (170), a holder (180) and a motor base (190).

The lens unit (110) may include a blocking member (113) for blockinglight among a plurality of lenses (111) and a plurality of lenses (111),and a spacer (115) for maintaining a gap among the plurality of lenses(111).

The barrel (120) functions to protect the lens unit (110) by beinginserted into the lens unit (110) and is formed at a bottom peripherywith a screw thread (123). The bobbin (130) is formed with a screwthread (133) at an inner side corresponding to the screw thread (123)formed at the barrel (120) to be coupled to the barrel (120) through thescrew thread (133) and wound with a coil (135) therearound.

The magnet (140) is discretely positioned from the coil (135) of thebobbin (130). In a case a current is applied to the coil (135) of thebobbin (130) to a predetermined direction, an electromagnetic force isgenerated from a magnetic field of the magnet (140), whereby a force isgenerated to linearly move the bobbin (130) and the barrel (120) coupledto the bobbin (130) upward or downward. Focuses of the plurality oflenses (111) can be adjusted by adjusting the intensity of the currentand by adjusting position of the barrel (120).

At this time, a separate focus adjusting process is needed in the courseof assembling the barrel (120) and the bobbin (130) adjusting theposition of the barrel (120), because screw fastening method isemployed.

The infrared filter (150) is positioned at the bottom of the lens unit(110), and is also positioned inside a support (183) extended from aholder (180) supportively attached at a floor surface by an adhesive toa printed circuit board (170. described later), where light collected atthe lens unit (110) and removed of infrared component by the infraredfilter (150) is irradiated to the image sensor (160).

A floor surface of a motor base (190) is attached upward of the holder(180), where the motor base (190) may be contacted on an upper surfacethereof by a floor surface of the bobbin (130), in a case the bobbin(130) is moved downward, and serves as a support as the bobbin (130) islinearly moved upward or downward. The image sensor (160) is discretelypositioned at a bottom of the infrared filter (150) and converts anoptical image filtered of infrared component by the infrared filter(150) to an electrical signal. At this time, the image sensor (160) andthe lens unit (110) are aligned on the same optical axis.

The printed circuit board (170. PCB) is formed with a predeterminedelectrical pattern and a plurality of electrodes (not shown). The PCB(170) is attached to a rear surface of the image sensor (160) by anadhesive such as epoxy, and is electrically connected to the imagesensor (160) via a bonding wire (163).

FIG. 2 is a cross-sectional view illustrating a camera module having anauto focus adjusting function according to an exemplary embodiment ofthe present invention.

Referring to FIG. 2, a camera module (200) having an auto focusadjusting function may include a lens unit (210), a barrel (220), a VCM(Voice Coil Motor) actuator (230), a housing (240), a magnet supportblock (250), an infrared filter (260), an image sensor (270), a printedcircuit board (280), and a bonding wire (290).

The lens unit (210) may include a plurality of lenses, a blocking memberfor blocking light among a plurality of lenses and a spacer (not shown)for maintaining a gap among the plurality of lenses. The barrel (220)functions to protect the lens unit by being inserted into the lens unit,and is attached at a periphery by a coil (237) wound on an inner yoke(231).

The barrel (220) may include a coil (237) at a periphery in variousshapes, in addition to the shape illustrated in FIG. 2. For example, thecoil (237) may be wound along a circumference of the barrel (220). Thebarrel (220) is attached with the VCM actuator (230), where the VCMactuator (220) includes yokes (231, 233, 235), the coil (237), a magnet(239) and a VCM actuator driver for driving the VCM actuator.

The magnet (239) is attached to the outer yoke (233) to be supported bythe magnet support block (250), and discretely positioned from the coil(238) attached to the barrel (220). The yoke formed with the magnet(239) and the coil (237) includes the inner yoke (231), the outer yoke(233) and the yoke support (235). The yoke is inserted into the housing(240), and a spring (245) is attached to an inner side of a portioncrosswise extended from an upper surface of the housing (240). Thespring (245) provides an elasticity to allow the barrel (220) tolinearly and vertically move.

A magnetic flux is formed from the magnet (239) toward the coil (237).For example, in a case a current flows in the coil (237) toward aground, a force is formed upwards of the coil (237) according toFleming's left hand rule. Therefore, the coil (237), the barrel (220)integrated with the coil (237) and the lens unit (210) inserted into thebarrel (220) vertically move. The coil (237) is connected to the VCMactuator driver for driving the VCM actuator, and current flowing in thecoil (237) is controlled by the VCM actuator driver.

Now, the VCM actuator driver will be described in detail with referenceto FIG. 3.

The infrared filter (260) is inserted into the barrel (220) from thebottom of the lens unit (210), where light collected at the lens unit(210) is removed of infrared component by the infrared filter (260) andis irradiated to the image sensor (270).

The image sensor (270) is discretely positioned at a bottom of theinfrared filter (260) and converts an optical image filtered of infraredcomponent by the infrared filter (260) to an electrical signal.

The printed circuit board (280. PCB) is formed with a predeterminedelectrical pattern and a plurality of electrodes (not shown). The PCB(280) is attached to a rear surface of the image sensor (270) by anadhesive such as epoxy, and is electrically connected to the imagesensor (270) via the bonding wire (290).

FIG. 3 is a block diagram illustrating a VCM actuator driver accordingto an exemplary embodiment of the present invention.

Referring to FIG. 3, the VCM actuator driver may include a POR (Power OnReset) unit (310),12C unit (320), a DAC (Digital-to-Analog Converter.330), a register (340), a memory (350) and an AMP (Amplifier. 360).

The POR unit (310) drives a device after a predetermined period of delayuntil a stable power is supplied at an initial power application. I2Cunit (320) receives an AF command algorithm signal by moving the lensunit (210) and performing the auto-focusing. The DAC (330) receives adigital signal and outputs an analog signal, and in the presentexemplary embodiment, the DAC (330) outputs a current in an analogsignal.

The register (340) inputs the digital signal outputted from the 12C unit(320) to the DAC (330), and includes a code value that indicates acurrent value in a bit value, and a matched current table. The memory(350) stores a hysteresis table which is a table showing an upwardposition value and a downward position value of the VCM actuator basedon each code value, and in the present exemplary embodiment, the memory(350) stores a lens position value to a gap of a reference distanceposition value or to a focus-matching point caused by a tolerance of thecamera module by adjusting a lens position to a focus-matching pointduring manufacturing of the camera module. Therefore, the DAC (330)outputs a current value based on the initial lens position value. TheAMP (360) performs a buffering function that gain-boots the output valueof the DAC (330).

FIG. 4 is a flowchart illustrating an example of a camera module havingan auto focus adjusting function according to an exemplary embodiment ofthe present invention.

Referring to FIG. 4, an image sensor is attached to the printed circuitboard (S410). Successively, the housing, the VCM actuator and the barrelinserted by lens unit are assembled on the printed circuit board (S420).The reference distance position value is calibrated by the assembledcamera module (S430).

Mode for the Invention

FIG. 5 is a flowchart illustrating a method of calibrating a referencedistance position value according to an exemplary embodiment of thepresent invention.

Referring to FIG. 5, the assembled camera module is set up to thereference distance position value (S431), where the reference distanceposition value is defined by a position of a lens focus-matched objectaccording to the camera module. Then, the lens position is adjusted fromthe reference distance position value to a focus-matched point using theVCM actuator based on resolution chart (S432).

To be more specific, a resolution specification relative to theresolution chart is detected from the reference distance position valueto upwardly or downwardly adjust the lens position to correspond to astandard resolution, whereby the lens position is adjusted to afocus-matched point.

Successively, the lens position is adjusted to a point where focusing isnot matched, and a lens position value to a gap of reference distanceposition value caused by tolerance of the camera module or to a pointwhere focusing is matched is stored in the memory (S433).

The calibration of reference distance position value according to theexemplary embodiment of the present invention may be implemented byconnecting the assembled camera module to a reference distance positionvalue calibration module performing the steps from S431 to S433.

Referring to FIG. 4 again, in a case the camera module is normallyoperated (S450), a gap of a reference distance position value caused bytolerance stored in the memory when the camera module is initially used,or a lens position value to a focus-matched point is read to adjust aninitial position of the lens by using the gap of the reference distanceposition value or the lens position value (S460).

The terms of ‘unit’ described in the exemplary embodiments may includesoftware components or hardware components such as FPGA(Field-Programmable Gate Array) or ASIC (Application Specific IntegratedCircuit), or a combination of these, and the operations and functionsdescribed herein can be implemented by the ‘unit’.

However, the ‘unit’ may not be limited to software or hardwarecomponents. For example, the ‘unit’ may be configured in addressablestorage media, or may be configured to reproduce one or more processors.

Therefore, for example, the ‘unit’ may include components such assoftware components, object-oriented software components, classcomponents and task components, and may include processors, functions,attributes, procedures, sub-routines, segments of program codes,drivers, firmware, micro codes, circuits, data, database, datastructures, tables, arrays and variations.

Functions provided in the components and the ‘unit may be coupled withlesser numbers of components and ‘units’, or may be further divided intoadditional components and ‘units’. Furthermore, the components and‘units’ may be implemented to reproduce one or more CPUs in a device ora security multimedia card.

All the functions described above may be implemented by software codedto perform the functions, microprocessors based on program codes,controllers, micro controllers, and processors such as ASIC (ApplicationSpecific Integrated Circuit). Designs, developments an implementationsof codes should be apparent to skilled in the art based on thedescription of the present invention.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

Industrial Applicability

The present invention has an industrial applicability in that functionof a bobbin of

VCM actuator can be implemented by a barrel and a spring, a pictureimage defect caused by optical tilt generated by tolerance of componentsis minimized by removing the bobbin, and assembly process of componentscan be reduced.

1. A camera module, characterized by: a camera module having an autofocus adjustment function, the camera characterized by: a lens unitincluding at least one lens; a barrel into which the lens unit isinserted, and connected by a VCM (Voice Coil Motor) actuator; and animage sensor discretely positioned from the lens unit to convert lighthaving passed the lens unit to an electrical signal, where the VCMactuator includes a gap of a reference distance position value which isa position of an object catering to a lens focal length according to thecamera module, and information on a focus-met lens position value, andadjusts an initial position of the lens by using the gap of referencedistance position value of the lens position value during operation ofthe camera module.
 2. The camera module of claim 1, characterized inthat the VCM actuator includes a VCM actuator driver for driving the VCMactuator, where the VCM actuator driver includes the gap of referencedistance position value or the information on the lens position value.3. The camera module of claim 2, characterized in that the VCM actuatorincludes a magnet forming a magnetic flux, a coil discretely positionedfrom the magnet, and attached to the barrel, and a yoke for attachingthe magnet and the coil.
 4. The camera module of claim 3, characterizedin that the VCM actuator driver is connected to the coil to move thebarrel attached with the coil by controlling a current flowing in thecoil.
 5. The camera module of claim 1, characterized in that the gap ofthe reference distance position value and the information on the lensposition value are obtained by calibration of the reference distanceposition value.
 6. A camera module, characterized by a lens unitincluding at least one lens; a barrel into which the lens unit isinserted; and a barrel-connected VCM (Voice Coil Motor) actuatoradjusting an initial position of the lens by using a gap of a referencedistance position value which is a position of a lens focus-met objector information on a lens position value at a focus-met area.
 7. Thecamera module of claim 6, characterized in that the VCM actuatorincludes a VCM actuator driver for driving the VCM actuator, where theVCM actuator driver includes the gap of reference distance positionvalue or the information on the lens position value.
 8. The cameramodule of claim 7, characterized in that the VCM actuator includes amagnet forming a magnetic flux, a coil discretely positioned from themagnet, and attached to the barrel, and a yoke for attaching the magnetand the coil.
 9. The camera module of claim 8, characterized in that theVCM actuator driver is connected to the coil to move the barrel attachedwith the coil by controlling a current flowing in the coil.
 10. Thecamera module of claim 6, characterized in that the gap of the referencedistance position value and the information on the lens position valueare obtained by calibration of the reference distance position value.11. The camera module of claim 6, characterized in that the lens unitincludes a plurality of lenses, a blocking member blocking light in theplurality of lenses, and a spacer maintaining a gap in the plurality oflenses.
 12. The camera module of claim 6, characterized in that the VCMactuator includes a coil positioned at a periphery of the barrel, amagnet discretely positioned from the coil to form a magnetic flux, acoil discretely positioned from the magnet, and attached to the barrel,and a yoke for attaching the magnet and the coil.
 13. The camera moduleof claim 12, characterized in that the coil is attached to the peripheryof the barrel.
 14. The camera module of claim 13, characterized in thatthe VCM actuator further includes an inner yoke wound by the coil. 15.The camera module of claim 14, characterized in that the VCM actuatorfurther includes an outer yoke attached by the magnet.
 16. The cameramodule of claim 15, characterized in that the inner yoke and the outeryoke are connected by a yoke support.
 17. The camera module of claim 16,characterized in that the inner yoke, the outer yoke and the barrel arepositioned inside a housing.
 18. The camera module of claim 17,characterized in that the barrel and the housing are connected by aspring.
 19. The camera module of claim 6, further characterized by animage sensor discretely positioned from the lens unit to convert lighthaving passed the lens unit to an electrical signal.
 20. The cameramodule of claim 19, further characterized by an infrared filter betweenthe barrel and the image sensor.